Nope. Dichromatic color deficiency is the most common form of color blindness, but about one in 20,000 people are completely unable to perceive color due to a variety of ophthalmic and neurological deficits. Even among dichromats, you can only reliably expect all users to be able to distinguish red and blue. It's probably not worth worrying about too much in most circumstances, but it is a relevant factor if you're designing safety-critical systems with a large user base.

Achromatopsia affects one in ~33,000 people. By comparison, any form of colorblindness affects one in 8 men and one in 200 women.

I'm not sure "someone using this system might see everything as the same shade of grey" is a realistic concern at those levels of incidence.

If you're going to worry about that, wouldn't you be more concerned about the operator being fully blind? And simply justify not hiring the vision impaired for this particular position?

"safety-critical systems with a large user base"

Surely a missile warning system would be operated by a very, very small number of people, on the order of twenty or thirty?

Black, blue, yellow, and white is usually a safe palette. Yellow-and-black diagonal striping is a fairly clear "exercise caution" indicator.